Weapons such as torpedoes can be dropped into a body of water from a high altitude by a helicopter, fixed wing aircraft and the like in an effort to damage and/or destroy an intended target. The impact of the water on sensitive array components within a nose section of the weapon can cause damage thereto and result in the failure of the weapon. Heretofore weapons have placed a protective nose cover over the forward end of the weapon in order to mitigate the water impact forces and prevent damage to the instrumentation. This force reduction is achieved primarily through streamlining of the nose shape through the addition of a pointed shape provided by the nose cover. However, for the sensitive array components to function properly, the protective nose cover must come off or be removed after the weapon has entered the water. One method that has been used to accomplish this task has been a cover that breaks up or fragments upon impact of the weapon with the water. However, limited success has been demonstrated by such a method since the nose cover has to be durable enough to protect the instrumentation during transport and from impact by other flying objects such as birds, and yet still provide reliable fracture upon water entry/impact.
In particular, frangible nose covers rely on the fracture strength of the material of construction in their design in that if the fracture strength is exceeded upon impact and/or entry into water, the nose cover fractures and the cover falls away from the weapon. However, the fracture strength of a given material can be highly variable, thus making such a protective nose cover that will fracture under specific conditions very difficult.
Heretofore frangible nose covers have been principally made from two types of materials—plastics and ceramics. The fracture strength of a given plastic typically varies with temperature, humidity, and time. Since none of these variables are controllable in an end use scenario, whether or not a plastic frangible nose cover fractures upon impact with water is highly variable. In contrast, ceramics are relatively stable with temperature, humidity and time. However small imperfections within or on a ceramic body can cause very large changes in the body's fracture strength. In summary, previous research and development of removable protective nose covers has been met with limited success.
As such, a protective nose cover that provides adequate protection during transport of the weapon and yet provides reliable removal upon entry into the water would be desirable.